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Technical MOTOR - Camel Hump Heads.

Discussion in 'The Hokey Ass Message Board' started by FWilliams, Jul 11, 2006.

  1. FWilliams
    Joined: Apr 24, 2001
    Posts: 1,983

    FWilliams
    Member

    Ahhh the camel hump...camel back...double hump ....double bump....fuelie.....known by a number of names and casting numbers, this GM head is either coveted or despised.


    with the introduction of the vortec heads, the camel hump is becoming a once again popular choice for a hot little small block mill, and in my opinion is the head of choice for a screamin small journal mill.

    I am not going to try and cover all the variations and styles that were made , but concentrate on the ones most likely to be found at the swap meet or the local paper. And try and cover some things to look for while checking out that "just rebuilt " piece.


    known mainly by the last 3 digits of their casting number, the most common ones to be found will be the

    461
    462
    186
    291
    492.

    the ones I am going to cover here are the 461 and the 462 and also the 291...the 492 is not as common but still found, it was the factory replacement for the camel hump and is virtually the exact same as the 462 casting ...in fact most of the heads are the same configuration as the 462 casting except for the 461.


    what i like most about the head is the fact that it flows OK out of the box, around 160 on the intake....can be made to flow much better with a little work...will except most any intake manifold that you can throw at it, and will also accept a whole slew of spring and retainer packages to custom tailor to any cam.

    the vortec while still a popular choice, has limited spring options ...and while having a newer burn combustion chamber, is still limited to lift and flow parameters....as well as limited intake choices. There are some new ones hitting the market all the time , but in my opinion if building a older style motor they just don't cut it. most of the write ups you read about them any more are in mags where you turn the page and there is a big ad selling said heads.

    I classify the head with the craze that surrounded the use of the 305 casting in circle track motors, the small combustion chamber instantly bumped up the compression in a stock rules class....the intake tract didnt flow worth a crap, but it was an easy and cheap way to boost compression.


    any way...enough of my .02....lets look at some heads.

    here are a few that have I have been working with as of late.....

    View attachment 204043



    the first thing I look at when I go to look at a set is what size valves do they have?....they will have either a 1.94/1.5 or a 2.02/1.6 valve set....either factory or machined afterward....a lot of the 1.94's that have had multiple or bad valve grinds, end up gettin cut bigger for the 2.02. in some very rare instances where a drag racer has had them, they could have a 2.05 intake, but it will be very rare to see this


    the 1.94/ 1.5 will have a definite area between the valves that you can plainly see



    View attachment 204044




    the 2.02/1.6 will look like the valves are touching....virtually no area visible between them.....when you see this you know that you have the big valves



    View attachment 204045



    the next thing to look at is what shape the valves and seats are in

    if the valves are sunken down into the valve seats, they have either been ground to much or to deep , or have pounded the seats down......the problem with sunken seats , are that they create all different valve stem heights.....especially if someone has been over agressive with the valve
    grinder..

    here is an example of sunken valves and then using a straight edge on the valve stem you can see the difference in the heights


    View attachment 204046 View attachment 204047



    what you would like to see are the valves sitting up, where you can actually see the valve edge or margin above the seat area.


    View attachment 204053



    next I look at the valve springs, have they been modified? and to what extent.


    a stock set up will have cast iron guides and valve springs with oil shields installed. they should have a small O ring style valve stem seal on the valve stem.......the oil shield is to help control the amount of oil the the O ring has to deal with...insureing enough oil gets to the valve guide ,but not to much

    the springs will look like this


    View attachment 204054


    most times when a valve job is done the valve guides are changed to either a thin bronze liner or a new thick wall bronze guide is installed.... a lot of times a positive type valve stem seal is installed when this is done...I do not like to see the positive type seal used if the stock oil shields are gonna be reused, you are not going to get the proper amount of oil to the valve guide by using this combination


    View attachment 204055



    if you are gonna use the postive type seal you should go to an after market retainer at least.


    View attachment 204056



    next thing to look at is the rocker stud set up . It will be stock pressed in stud.....

    pressed in stud that has been pinned......

    tapped for a screw in stud......

    .tapped and machined for a guide plate and screw in stud. I dont have any pictures of pinned studs....it really isn't done much any more...the first pic is a pressed in stud. You can see the boss the stud sits on is tapered at the top.


    in the next pic you can see where the boss has been machined to flatten it off and give a little more surface area then drilled and tapped


    finally the last pic you can see the boss has been milled down to accept the thickness of the guide plate and screw in stud.


    View attachment 204061 View attachment 204062 View attachment 204063



    it's nice to at least have the screw in stud for a performance application.


    a couple of other things I want to touch on briefly, if you are running the 2.02 valves and the valve area of the combustion chamber has not been unshrouded , you are more than likely flowing worse than of you had the 1.94 valves...there is nothing wrong with the 1.94 in a hot little street motor....you can usually pick these up cheaper , because everyone wants the 2.02.


    most of the ones that I find at swaps and what not have been done by racers that have moved up to a better head for their paticular class...they want to get little money back out of them . but in most cases they have had excellent machine work done......and you can get it at a fraction of the cost.....walk by the guys with the 600.00 dollar core heads ...matching corvette numbers,,, yada yada yada, these heads are not getting those kind of prices any more...



    lets go find a set of heads........
     

    Attached Files:

  2. FWilliams
    Joined: Apr 24, 2001
    Posts: 1,983

    FWilliams
    Member

    I picked up this set of 291's the other day,, they had the 2.02 valves and the chambers had been unshrouded....they had fresh comp cam springs and retainers and had also been cut for screw in studs and plates


    View attachment 204068

    View attachment 204069

    View attachment 204070



    I diassembled them and checked them over...they had hardened exhaust seats and everything looked good, spring heights are even, studs are machined straight.



    the fellow I bought them from had took them off his 383 stroker, they just were not enough head for it.he gave me the name of the machine shop that had done the work, everything looked good so I brought them home and opened them up, checked the seat runout, guides etc


    they have had a little pocket porting done,valves unshrouded, everything looked good so a little elbow grease and I had them cleaned up, these prolly have 4 or 5 hrs run time at most , and are everything the seller said they were.



    View attachment 204071 View attachment 204072 View attachment 204073



    after checking spring pressures and valve seats, a little more cleanup I shot them with a little chevy orange VHT


    View attachment 204074




    they started to look so good I rolled them over and installed the Glenn Hayes/Federal Mogul sponsored roller tip rocker arms.....


    and there you have it . the 2006 HAMB DRAGS raffle engine heads

    291 casting
    2.02/1.6 stainless valves
    pc seals
    comp springs/ retainers/ locks
    bronze valve guides
    screw in studs
    guide plates
    pocket ported
    roller tip rockers


    these things cost us less than ONE vortec head, and this is not a rare deal , but i believe the 4th set that I have picked up this year, and a couple I passed on at the last swap, cause I just didnt need them...., oh I have walked by some junk to find them but keep your eyes and ears open and I am sure you will run across a set just as nice.




    View attachment 204074 View attachment 204075 View attachment 204076




    Fred
     

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  3. Irish Dan
    Joined: Jan 19, 2006
    Posts: 1,231

    Irish Dan
    Member

    Running the risk of sounding like I'm preaching to the choir, the only other thing I would do to prep those heads would be to deburr them with a wire wheel on an electric drill. I've owned a lotta' "double humpers", & I highly recommend them if for no other reason, the fact that they "breathe" so well! My 2 cents only.
     
  4. FWilliams
    Joined: Apr 24, 2001
    Posts: 1,983

    FWilliams
    Member




    I have run this style head since the late 70's. On my own personel stuff I have never had hardened exhaust seats installed. I use to add a little lead additive every fifth tank or so, but a lot of times would forget about it...I never saw any ill effects later on when I pulled them apart.

    I leave it up to the individual, if they are gonna feel more comfy with them , by all means install them. If they are happy with adding the additive . go for it.
    without knowing, and it if it worries you, I would toss a little additive in there once in awhile.



    Fred
     
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  5. Roothawg
    Joined: Mar 14, 2001
    Posts: 14,831

    Roothawg
    Member

    I have heard that the race fuel still contains lead and it can be added and ran through just like the additive. I don't know if this is true or not but at 5 bucks a gallon, it's not much more than 7-11 gas....
     
  6. FWilliams
    Joined: Apr 24, 2001
    Posts: 1,983

    FWilliams
    Member




    you can get them to fit over the stock guide boss, but they should be tailored to the spring package....

    if the springs require a smaller diameter seal, or the lift of the cam requires the top to be cut down so there is no retainer hitting the top of the guide issues, then they will have to be machined for that application.



    Fred
     
  7. squirrel
    Joined: Sep 23, 2004
    Posts: 26,357

    squirrel
    Member

    On the hardened seats thing, it depends on the way you use the engine, also. If it's in a heavy car or truck where the engine has to work hard and that will see a lot of miles, the seats will be more likely to get hammered, and hard seats might be a good idea. For a light car that won't get too many miles on it, it shouldn't be a problem to run the heads without hard seats.
     
  8. stan292
    Joined: Dec 6, 2002
    Posts: 857

    stan292
    Member

    Thanks Fred!

    Great stuff. These heads were the "only way to go" back in the day - plentiful and resonably priced, yet surrounded by the usual clueless lore and mis-information that is so often part of "hot-rod tech" at bench-racing sessions. I'm the first to admit being guilty of using the "double-humpers" without really knowing the facts - or necessarily doing the right thing.

    Thanks much for the "refresher course" and straight scoop on these classic performance parts.

    My first head-porting job was on a set of "camels" - and laughable, I'm sure - as far as performance gains went (they looked cool though! - LOL). How about some of your down-to-earth advice regarding "home" porting work (i.e., port matching, general "clean-up", etc.) for these heads? Is there much worthwhile a person can do on his own - or is it best to rely on the pros all the way?

    P.S. Where can you get the "lead additive" that some of the posts here mention?
     
  9. MIKE-3137
    Joined: Feb 19, 2003
    Posts: 1,560

    MIKE-3137
    Member

    Great info, can you shed some light on what is different about the 461 "X" heads, as apposed to the normal 461 castings?
     
  10. Hot Rod To Hell
    Joined: Aug 19, 2003
    Posts: 3,031

    Hot Rod To Hell
    Member
    from Flint MI

    Hey Fred, I haven't worked at a machine shop, or even had any machine work done in YEARS, so I don't know what shops are charging these days;
    So here are a couple of questions...

    If you had more than one set of heads you wanted to "hook up" (cut for studs/guideplates, cut for PC seals, maybe bigger spring seats, etc), would you be further ahead to purchase the cutters and do it yourself?

    Would it be worth picking up the stuff to put in bronze liners, or are full guides the way to go?

    If you're fortunate enough to have a mill, is there any reason a home machinist couldn't tackle the "closer-tolerance" jobs, such as replacing guides and hogging bowls for larger valves?

    You can pick up a used seat grinder set for $100-$200 on Egay; while it's not as consistent as something like a serdi, is there any reason that it wouldn't be great for a home workshop?

    When I was working in a machine shop, I preferred the stone setup for my own heads, because I had more control over the widths of the individual angles, as well as being able to dress stones to different angles to get exatly the radii I wanted

    Is this still considered a "good" setup for unshrouding valves, or is there a better way now?


    It seems to me that for about $600 or so you could purchase most of the tools necessary to hot rod a set of SBC heads... how many heads would you have to do to offset the initial investment?



    If it makes any difference in how you answer my questions, I was an ASE certified auto engine machinist; but I let it expire, because there's MUCH more money to be had poking holes in people!:eek:



    Thanks!
    Steve
     
  11. flt-blk
    Joined: Jun 25, 2002
    Posts: 4,405

    flt-blk
    Member
    1. S.F.C.C.

    what is the threshold that requires roller tip rockers?

    I have a pair of World Products SPII heads and a medium lift Comp cam on a
    383ci SBC, my machine shop suggest stamped rockers would be fine on the
    street so that's what I went with.
    TZ
     
  12. FWilliams
    Joined: Apr 24, 2001
    Posts: 1,983

    FWilliams
    Member

     
  13. Roothawg
    Joined: Mar 14, 2001
    Posts: 14,831

    Roothawg
    Member

    Fred, do you mind explaining shrouding and how to remedy this?
     
  14. FWilliams
    Joined: Apr 24, 2001
    Posts: 1,983

    FWilliams
    Member


    whats the rest of the number before it. there was a 046, but it was used on the 265
     
  15. FWilliams
    Joined: Apr 24, 2001
    Posts: 1,983

    FWilliams
    Member



    i have only actually seen 3 pair of the 461x heads, and of those 3, only one had not been ported to hell...the best I could find was that the intake runner was a tad bit larger maybe 170-175 instead of the usual 160...and the x came directly after the casting number, not some where else on the head. I have guys try to sell me 461's that are supposed to be the x version because thay have an x on the head somewhere else. these all had 461X
     
  16. Aman
    Joined: Dec 28, 2005
    Posts: 2,525

    Aman
    Member
    from Texas

    Racefab thanks for the article. It's better than any magazine I've picked up lately. I have a couple questions if you don't mind. 1) Over the years, I've seen heads with humps and with triangles. Singles and doubles. Are they the same or is there a secret code there somewhere? 2) These heads you show, are they for early model V-8s without the mounting holes or for the later model heads. I have a 77 model 350 4 bolt main block I need a good set of heads for and was wondering if these will work. I prefer the mounting holes. 3) How much performance gain will I see with these heads over the 1.94's for a street driven model A. Thanks again, and I appreciate any input you may offer.
     
  17. squirrel
    Joined: Sep 23, 2004
    Posts: 26,357

    squirrel
    Member

    The bracket holes became standard on the 1969 models, when they went to the long water pump. Some (very few) earlier heads had them....I have a pair of stagger bolt powerpacks with the holes!

    A triangle is a power pack head, small ports, small valves (1.72/1.50), closed chamber heads. Double humps are the big valve, big port, closed chamber heads.
     
  18. FWilliams
    Joined: Apr 24, 2001
    Posts: 1,983

    FWilliams
    Member

    basically the edge of the valve is extremley close to the combustion chamber wall, the intake charge is restricted and cannot flow around the head of the valve. by machining the combustion chamber wall away from the valve .,..you open up some area for the intake charge to flow...this is a VERY basic explanation


    here you can see the shiny area where the chamber wall has been machined away


    View attachment 204410
     

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  19. FWilliams
    Joined: Apr 24, 2001
    Posts: 1,983

    FWilliams
    Member

    many e mails on the difference between the 461 and the 462


    the 461 was the original camel hump, it had a spark plug location very close to the edge of the combustion chamber....also the combustion chamber had a little different shape than the D shape of the 462


    the 462 and pretty much all the following camel hump heads had the D shaped chamber, and the spark plug location was moved with a large quench pad adjacent to it....these are the heads to use if you are going to run domed pistons, the 461's usually have some interference with domes and spark plugs.




    461

    View attachment 204412




    462


    View attachment 204413
     

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  20. FWilliams
    Joined: Apr 24, 2001
    Posts: 1,983

    FWilliams
    Member


    if you machine out the same amount you will keep the chamber sizes even...you could do it with a rotary file ....but I woud keep checking the combustion chamber volume and try to keep everything even...or as close as possible



    Fred
     
  21. 32chevysedan
    Joined: Jun 11, 2006
    Posts: 377

    32chevysedan
    Member
    from Texas

    Like said in a previous post 461X heads flow a little more than the originals, they are also twice as hard to find these heads were only available from 60-63 and are 172cc intake runners with 62cc combustion chambers instead of the original 64cc. Another great factory head is the 041 or 041X, these are the exact same casting(intake runners and combustion chamber design) as your double humps but have a right angle triangle instead of the camel humps. The X means the same here that it flows better. Just my 2 cents...........
     
  22. squirrel
    Joined: Sep 23, 2004
    Posts: 26,357

    squirrel
    Member

    69 is large journal

    the camel hump 1.94 heads were most common...yeah, they were on the 300 hp motors

    as usual, you have to pull the heads to see what you really have, a lot has happened to many pairs of heads over the past 40 years
     
  23. BriggsBodied28
    Joined: May 13, 2006
    Posts: 88

    BriggsBodied28
    Member

    Great post RACEFAB. I'm left with a question though. In referencing both the larger 2.02" intakes, and the larger runner area of the 461x, you've stated that they "flow better." This may confuse some folks into thinking that bigger is always better. In this case, bigger usually equates to a significant loss of port velocity throughout the majority of the powerband until the revs really get up high.
     
  24. FWilliams
    Joined: Apr 24, 2001
    Posts: 1,983

    FWilliams
    Member


    mmmm, havent seen this thread in a while, will have to go back and read thru, but I dont think I said that the 461x's "flowed" better... I think i said they have more runner volume....170 to 175 cc on the ones I have cc'd compared to the 160cc of the stock 461



    I also touched on how a smaller 1.94 valve could actually outflow a shrouded 2.02
     
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